Pregnancy Due Date Calculator
Calculate your baby's estimated due date using one of four methods. Get your personalised Nigerian antenatal care schedule and download it to your calendar.
How the Due Date Calculator Works
Method 1: Last Menstrual Period (LMP)
The most common method. We add 280 days (40 weeks) to the first day of your last period. If your cycle is not 28 days, we adjust the calculation. For example, a 30-day cycle adds 2 extra days. This is the same method used by doctors across Nigeria.
Method 2: Conception Date
If you know when you conceived, we add 266 days (38 weeks) from that date. This is useful if you were tracking ovulation or know the exact date of conception.
Method 3: Ultrasound
If you've had a dating ultrasound, enter the date and the gestational age measured at that scan. Early ultrasounds (before 12 weeks) are the most accurate for dating.
Method 4: IVF/ICSI Transfer Date
For IVF pregnancies, the due date is calculated from the embryo transfer date. A Day 5 blastocyst transfer means we subtract 19 days to find the equivalent LMP date, then add 280 days. For Day 3 transfers, we subtract 17 days. See our dedicated IVF due date calculator for more details.
Frequently Asked Questions
How is the due date calculated?
The due date is calculated by adding 280 days (40 weeks) to the first day of your last menstrual period (LMP). If your cycle is longer or shorter than 28 days, the calculation is adjusted accordingly.
How accurate is a due date calculator?
Due date calculators provide an estimate. Only about 5% of babies are born on their exact due date. Most babies arrive within two weeks before or after the estimated date. An ultrasound in the first trimester provides the most accurate dating.
What is the antenatal care schedule in Nigeria?
Nigeria follows the WHO focused antenatal care model recommending a minimum of 4 visits: a booking visit before 16 weeks, then visits at 24-28 weeks, 32 weeks, and 36 weeks. High-risk pregnancies may require additional visits.
Can I use this calculator for an IVF pregnancy?
Yes! Our calculator includes an IVF/ICSI tab. Simply enter your embryo transfer date and whether it was a Day 3 or Day 5 transfer, and we'll calculate your due date accordingly.
When should I book my first antenatal appointment?
In Nigeria, it is recommended to book your first antenatal (booking) visit before 16 weeks of pregnancy. Early booking allows for important baseline tests and early detection of any risk factors.